trying to understand the JSModuleReferenceContributor class...

EmberAddonReferenceContributor.kt

class EmberAddonReferenceContributor : JSModuleReferenceContributor {
    override fun getCommonJSModuleReferences(unquotedRefText: String, host: PsiElement, offset: Int, provider: PsiReferenceProvider?) =
            emptyArray<PsiReference>()

    override fun getAllReferences(unquotedRefText: String, host: PsiElement, offset: Int, provider: PsiReferenceProvider?): Array<FileReference> {
        return EmberAddonFileReferenceSet(unquotedRefText, host, offset, provider).allReferences
    }

    override fun isApplicable(host: PsiElement) = host is ES6FromClause
}

class EmberAddonFileReferenceSet(unquotedRefText: String, host: PsiElement, offset: Int, provider: PsiReferenceProvider?) :
        FileReferenceSet(unquotedRefText, host, offset, provider, false, true, DialectDetector.JAVASCRIPT_FILE_TYPES_ARRAY) {

    override fun useIncludingFileAsContext() = false

    override fun computeDefaultContexts(): MutableCollection<PsiFileSystemItem> {
        val result = mutableListOf<PsiFileSystemItem>()

        if (!this.pathString.startsWith('.')) {
            result += this.element.containingFile.originalFile.virtualFile.parents
                    .map { it.findChild("node_modules") }
                    .filterNotNull()
                    .map { element.manager.findDirectory(it) }
                    .filterNotNull()
        }

        return result
    }

    override fun createFileReference(textRange: TextRange, i: Int, text: String): FileReference {
        val t = if (i == 0) "$text/addon" else text
        return EmberAddonReference(t, i, textRange, this, "ember-addon.js", true)
    }
}

class EmberAddonReference(text: String, offset: Int, textRange: TextRange, fileReferenceSet: FileReferenceSet, newFileTemplateName: String, isSoft: Boolean) :
        JSFileReference(text, offset, textRange, fileReferenceSet) {
}